Method of manufacturing tin plate



March 11, 1941. c. G. Pneus 2,234,195

METHOD OF MANUFACTURING TIN PLATE Filed Jan. 12,- 1938 2 SheetsFSheet 1 H I r ATTORNEYS March 11, 1941. c. G. PREIS 2,234.195

METHOD 0F MANUFACTURING TIN PLATE Filed aan. 12, 195s z sh'ets-sneet 2 INVENTOR Patented `Mar. 1 l, 1941 METHOD F MANUFACTURING TIN PLATE Carl G. Preis, New York, N. Y., assignor to American CanCompany, New York, N. Y., a corporation of New Jersey Application January 12, 1938, Serial No. 184,689

1 Claim.

The present invention relates to preparing sheets of tin plate in the tin plate mill for subsequent use in the manufacture of tin can parts or other non-rectangular articles and has par- 5 ticular reference to preparing a sheet of predetermined configuration which can be used subsequently by the can manufacturer with a minimum of waste. I

In large scale production of tin can parts in a can manufacturingplant where millions of articles are produced by punching, blanking and forming from tin coated sheets any areas of the sheet which are notcut out at that time or later,

whereby fully tinned sheets having two scroll edges are cut from the web without great loss of represent waste and become scrap which has a' very small resale value. Obviously even small portions of waste in a single sheet when multiy plied by the millions of sheets used by a Asingle large can .manufacture for example become a serious loss, and many attempts have been made to minimize such waste. In the present invention it is contemplated to save this waste at the tin mill by iirst removing such areas from the sheet as will not be of valueY in subsequent cutting of the sheet and by the removing of the stock at a time and place where it has a value, i. e., where it can be put back again into the melting pot and where added expense such as scrap handling and transportation charges can be `entirely avoided. The making of black iron stock in web form has now become common practice in the tin mills and such form of tin plate production is best adapted tothe saving of waste according to thepresent invention.

An object of the invention is the provision of .a method of preparing sheets of tin plate from web material in a manner that will provide sheets having the greatest usable cutting areas` for the subsequent production of articles.

A further object of the invention is the provision of such a method wherein sheets having two or more scroll edges are produced directlymaterial; v

Fig. 2 shows a similar view wherein the steps are slightly changed in order of sequence of oper- 5 ation, fully tinned sheets having more than two scroll edges being produced from a web of material; and

Fig. 3 is a schematic plan layout of certain cutting of tin plate when used in the manufacture l0 of circular articles.

The drawings illustrate two forms of procedure both insuring practically the same production of a sheet of tin plate in which the sum of the cutting areas of articles subsequently to be 'l5 made from the sheet closely corresponds with the total area of the sheet as it is provided at the tin mill. In the arrangement of procedure according to Fig. 1, a web of black iron stock is rst tinned before it is cut into individual sheets, 2 the operation of cutting being done along a scroll line of cut to minimize waste of the sheet and prepare it for more eilcient subsequent use by the can manufacturer or otherwise. When the method steps are employed accordingto this disclosure the resulting individual sheet is provided with two oppositely disposed scroll edges and the side edges of the sheet are left straight.

In Fig. 2 a slightly different procedure is 30 used although the results are substantially the same. In this second modification of the invention a webof black iron stock is rst notched along its side edges, is then transversely divided into individual sheets by a scroll line of cut and the resulting individual sheets have four scroll edges. y'

These sheets are passed through a tinning op- ''ration so that the sheet 'as finally prepared by the tin mill is tin coated and properly edged, this o time with four scroll edges. 'Ihis form of sheet for some purposes has a higher cutting eiliciency inasmuch as more of the waste is removed by the scroll cutting of the side edges of the web prior to its being divided into individual sheets. 45

In order t'o further explain the eicency of cutting of non-rectangular work as by a can manufacturer, Fig. 3 is used to disclose schematically a typical layout of cutting -circular articles from the sheet. This view furthermore suggests 5g the common practice in can manufacturing procedure of rst dividing a sheet into scroll strip form suitable for automatic feeding into and through cutting, blanking or forming die mechanism at which time the eiective cutting .area is izo ` 5 with straight side edges b. Irrespective oi' the precise steps of the inethod used, the web is divided into individual sheets c by cutting along a transverseline extending from one side to the other. Such a line of cut is made in scroll form..

` this transverse-'cutting"being 'designated by the letter d.

' The articles to be cut from the sheet are'shown as being circular, although any shape not rectangular` will more or less dictate the type of layout. The circular shape or blanking line of cut is designated in Fig. 3 by the letter e. The available cutting areas for the circles may be a1;- ranged in two or more rows and alternate rows are staggered according to well known practices inthe can making art.

When the individual sheet c is received at the can manufacturers plant, if the cutting is to be done in automatic strip feed presses, the sheet is ilrst divided longitudinally by' other scroll lines of cut f, producing what is known in the art as f a scroll strip g. Each of the scroll strips illustratedin Fig. 3 contains two rows of cutting areas and'this form is usedvin a double die cutting press. .In many cases more than two rows are used and gang dies may then be utilized. AIn many cases a single row of cutting areas is found advantageous for a single die automatic strip feed press. In that case the double row strip y would be further longitudinally divided along scroll lines of cut in order to produce a single row of available cutting spaces.

In the illustration shown in Fig. 3-it is constemplated to cut an edge/scrap h by means of a scroll cut on one edge. Two outside edges of the sheet would be so cut by the scroll lines 7'. Such an operation of scrap cutting willbe used in the first suggested phase of the present invention, that is, according to the showing in Fig, 1. In Fig. 2 the can manufacturerwill not d o any edge cutting .to produce the scrap h since the sheet as finally delivered tothe can manufacturer by the tin mill would have all four of its edges cut along scroll lines.

When the steps of Fig. 1 are carried out a web of material such as black iron stock, designated by the numeral 2 I, may be fed from a reel or roll 22 of such material. The roll may be carried on a shaft 23 from which it is univound as theweb passes through its ooperations in the tin mill. 'I'he shaft 23 may be suitably journalled in bearings formed in a main frame 24. Feed rollers 25 l are used to draw the web from its roll and these rollers may be mounted and rotated in any suitable manner. 1

The web .2| after passing through the feed roll- -ers 25 advances over a'horizontal guiding roller 21 suitably mounted and rotated. The web 2| after passing over the roller 21 is moved down into a vertical position where it enters into a tinning operation. The tin bath andframe there-- fore is schematically suggested in the drawings as an -enclosing vessel. 3| formed with vertical side walls 32'and a bottom'33. j

-Vessel 3| holds-the' usual molten tin and on the surface-of the liquidV metal there will be'the usual palm oil as is'well knownfin the practice of tin plate coating. To-assist the web 2| in lthe proper travel through the tinning operation,

175 pairs of guiding rollers 34 Vmay be"si1itably mounted within the vessel. A curved guide plate 36 is located within the vessel and assists'in properly guiding the sheetv through the tinning operation.

'Ihe tinned web having both' sides properly 5 coated passes over a roller 4| and thence through a. pair of pull rollers 42 suitably mounted in the frame of the machine. Adjacent the pull rollers 42 is a pair of secondary pull rollers 43 and the web of material 2| is so fed'into the machine 10 as to form a loop 45. The pull rollers 42 are continuously rotated in proper time with the other continuous operations relative to the web Y as it travels between supply reel 2l and the pull rollers 42. l5

The rollers 43 are intermittently rotated and the loop 45 allows for the continuous advancement of the web into the rollers 42 and for the step movement of the web from the rollers 43 this being a well known expedient of web feeding. 20 'I'he rollers 43 push-the web into a scroll cutting die mechanism 41 mounted adjacent the roller 43. This mechanism 41 includes a vertically movable cross head 5| which carries the movable element of a scroll die 52. `The rollers 43 when 25 at rest, hold the end of the web in proper position for cutting beneath the movable die 52.

The movable die element .52 cooperates with a stationary die element 53 which is mounted within the scroll cutting mechanism 41. web is moved between the dies 52, 53 to bring it into proper cutting position and a transverse scroll cut'made by the dies (the cut d of Fig. 3) -severs from the web an individual sheet 55. After the sheet 55 has been severed from the end 35 of the web it is conveyed away to any suitable place of deposit as` by a continuously moving conveyor belt 51 which in the machine and adjacent the cutting mechanism 41 may pass over a o suitable roller 58.

The sheet 55 thus :has straight side edges b,

Abut the two end edges are formed with the scroll line of cut d. In thisY condition the sheets is suitable for subsequent artlclemanufacture. Ac- 45 cording to this practice of operation, as exemplified by Fig. 1, there is no waste in the tin mill but the scroll cutting of the ends of the sheet provides a more efficient sheet for 4the purpose of subsequently cutting circular or other non-rectangular articles therefrom. The total area of the 1 divided sheet more nearly corresponds with the combined article cutting areas within thesheet, than within a sheet having only straight edges such as is the usual practice in tin plate manufacture today.

The alternate manner of providing individual `scroll sheets having a high cutting eiiiciency is disclosed in Fig. 2 and for some jobs this procedure will be preferred. The web 2| is fed as no before from a reel 22. A pair of feeding rollers 6| is suitably mounted and rotated to feed the "web through the operations of the machine.

These rollers may be rotated continuously and the web after passing -through the rollers is formed in to a lloop 62 fromv which it passes through intermittently rotated pull rollers 63 which are suitably mounted and rotated to effectl the cutting operations subsequently following. f

In this form of procedure the web 2| as ad- 70 vanced by the roller 63 rst moves into position between notching die mechanisms 55-V arranged on opposite sides of the sheet and the web edges are notched as the web is brought to rest. 'I 'hese mechanisms include proper' --m'ovable cutting dies 75 The 66 which cooperate with lower stationary dies to cut out a waste or scrap section. This continues as the web advances land there results notched or scroll edges of the web as at 61. 'I'his provides the scroll edges i previously referred to in the description relating to Fig. 3 above. The loop 62 allows for the continuous feeding of the web into the rollers 6I and for the intermittent movement of the web through the rollers 63.

The notched end of the web after passing through the mechanism 65, passes into a sui-table scroll cutting die mechanism 6l, this corresponding in operation to the mechanism 41 referred to in connection with Fig. 1. A movable cross head 1I carries an upper scroll die 12 which, when the web is at rest beneath, moves down and cuts through the web, cooperating with a stationary lower scroll die 13. This die operation transversely cuts across the web in a scroll line of cut (out d as shown in Fig. 3) and severs an individual sheet 15 from the web.

Af-ter the individual sheet 15 is cutfrom the web it falls upon a continuously movable belt 'I1 which passes over supporting and driving rollers 18 actuated 4in suitable manner -to eiect removal of the sheet from the cutting mechanism.

The individual sheet is then passed through a tinning operation which is analogousy -to the operation referred to above. In this instance the sheet may pass under a curved guiding plate 8| and over ahcontinuously rotating roller 82 mounted in a suitable tinning vessel 83. Such a vessel is herein shown as formed with vertical side walls 84 and a bottom 85 and is adapted to hold the molten tin. The roller 82 guides the sheet through a pair of feed rollers 88 mounted inside of the tin bath, it being understood that the molten tin and the palm oil for -the usual tinning operation are contained within the vessel I3.

The sheet 15 after leaving the rollers 86 passes over a curved plate 81 mounted within the tinning vessel 83 and thence into rollers Il which advance it over an inclined wall Il which may be an integral part of one of the vertical walls M of the tinning bath. The sheet passes from the inclined wall 9i and falls onto a continuously moving discharge belt 95. At the machine end such a belt operates over a roller 86. This :belt removes the sheet from the tinning bath into a suitable place of deposit.

been removed in the tin mill, may be put back into the melting pot and does not represent a loss as is present when old methods of straight edged sheets are made.'

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and lt will be apparent that various changes may be ni. le in the steps of the process described and their order of accomplishment without departing from :the spirtt and scope of the invention or sacrificing all of its material advantages, -the process hereinbefore described being merely a preferred embodiment thereof.

I claim:

A method of manufacturing tin stock to avoid waste of material in subsequent article cutting,

.which comprises, immersing and continuously passing black iron stock in sheet form through a molten tin bath, and scroll cutting opposite edges of said stock as a separate step vin immediate conjunction with and incident to the .tinning operation while simultaneously severing said stock into individual sheets, whereby the total area of the scroll cut sheet corresponds closely to the total number of articles to be formed therefrom. and the presence of undue waste scrap during the subsequent formation of such articles from said tinned sheet, and lthe necessity of returning said scrap .t'o a tin mill, is eliminated.

CARL G. PREIS. 

